Starting-switch.



C. F. CUNO.

STARTING SWITCH.

APPLICATION FILED nc.21, I915.

Patented Sept. 12,1916. 2 SHEETS-SHEET 1.

Czar/e; 2/10. %4; attoznzvd C. F. CUNO.

STARTING SWITCH. APPLICATION FILED 050.27, 1915.

1,197,800. Patented Sept. 12, 1916.

2 $HEETSSHEET 2.

e C /zar/w' [fa/20 UNITED STATES- PATENT omen.

CHARLES E. CUNO, OF MERIDEN, CONNECTICUT, ASSIGNOR TO THE CUNO ENGINEERING CORPORATION, OF MERIDEN, CONNECTICUT, A CORPORATION OF CONNECTICUT.

STARTING-SWITCII.

Specification of Letters Patent.

Patented Sept. 12, 1916.

Application fi led December 27,1915. Serial No. 68,625.

of high current carrying capacity which will be positive in action, compact in size, and which will be "thoroughly protected both from a mechanical and electrical standpoint.

Other objects of the invention are to insure firm positive electrical engagement of the movable contact with the relatively stationary switch contacts and to protect the current carrying contact from injury by arcing and burning out.

In the accomplishment of the foregoing and other objects, I employ, in connection with the relatively stationary switch contacts, a movable spring pressed plunger car rying a main contact for bridging the switch contacts, and in addition,-a supplementary contact for relieving the maincontact of the arcing attendant-upon'breaking of the circuit? The main and supplementary contacts are preferably mounted so as to be selfadjusting on the plunger which supports them so as to accommodate themselves automatically to a proper engagement with the separated switch contacts.

The current carrying elements are all preferably inclosed in a waterproof casing and the entrance of moisture or foreign matter into this casing through the bearing of the operating plunger is guarded against by providing this plunger with a cap which slips over a hub carried by the casing and surrounding the plunger.

A special feature ofthe invention resides in the employment of the space between the plunger and the hub surrounding it 'as a housing for the spring which operates to withdraw the plunger from the contact making position.

.Various other features and details of construction will appear; as the specification proceeds, attention-being directedto the accompanying drawings which illustrate a been removed in this figure.

practical and preferred form of the inven- In these drawingsz Figure 1 is a view in 1' side elevation illustrating a switch embody- .ing the invention mounted in a customary position in'the floor of an automobile for operation by the heel of the driver. Fig. 2

is a-vertica'l sectional view of the same. Fig. 3 is a sectional view taken through the lower portion of the switch casing substantially on the plane of the line 3-3 of Fig. 4. Fig. 4 is atop plan view of the lower member of the switch casing. Fig. 5 is a bottom plan view of the upper member of the switch housing showing the main and supplementary contacts on the lower end of the operating plunger. Fig. 6 is a bottom plan view of the lower part of the switch housing, the relatively stationary switch contacts having Fig- 7 is a broken sectional view illustrating the operation of the main and supplementary contacts. Fig. 8 is a drop perspective view of the main and supplementary contacts and the elements for mounting the same.

- In Fig. 1 the invention is shown employed as a heel switch, it being for this purpose mounted in the floor board 10 of an automobile with the operating stem or plunger 11 thereof disposed in'position to be conveniently engaged by the heel of the driver. The switch is, in such a case, conveniently secured in place by bolts 12 passed through openings 13 in the flange of the switch casing, said bolts engaging at the upper side of the floor with a suitable face plate or escutcheon 14.

The switch parts are housed in a casing consisting in the present disclosure of a cupped base or lower portion 15, and a top plate 16, said parts being suitably fastened together, as by means of screws 9 engaged in the abutting flanges 17 and 18 of said two parts, a gasket 19 preferablybeing interposed between these flanges to make the casing water-tight and dust-proof.

The relatively stationary switch contacts are designated 20 and 21, these contacts be ing on a suitable insulating base 22. The

. means shown for securing these switch contacts in placeare'the screws 2? passed up through the bottom of the housing lnto engagement with the contacts, said screws being-insulated from the casing by suitable means such as insulating bushings or washers 24.

The switch contacts are made sufliciently massive to carry the relatively heavy current, which motor starting swltches .of this character are ordinarily called upon to trans-- mit, and to gain the necessary contact surface the contact faces of such members are preferably made semi-circular in form, as most clearly indicated in F ig. 4. These two semi-circular contacts are electrically separated from each other, in the present instance, by means of an insulating air gap 25. Attachment of the circuit connections is usually made to the switch contacts through the medium of binding screws 26, said screws serving to clamp the terminal lugs 27 on the ends of the circuit connections direct to the lugs or extensions 28 of the contact members which project downwardly through an'open ing 29 in the bottom of the switch housing.

The movable switch contacts which serve to bridge the relatively stationary contacts are carried by the rod or plunger 11 guided in the hub extension 31 of, the top plate 16, said plunger being normally held in its uppermost position by means of a spring 32 seated in a recess 33 in the hub surrounding the plunger, bearing at its inner end against the inner end of said recess and at the outer end against a shoulder on the plunger. The shoulder on the outer end of the plunger is provided in the present disclosure by a cap 34 secured to the outer end of the plunger and havinga dependent flange which slides over and makes a close joint with the reduced portion 35 at the outer end of the hub. This makes a sliding joint which excludes moisture, dust and other foreign matter, and the shoulder 36 at the inner end of the reduced hub portion serves as a stop when engaged by the dependent flange of the cap 34 to limit the inward movement of the plunger. It will be seen further that this particular form of'joint will serve to shed any dirt that maybe deposited on the top of the plunger from the heel of the oper-f ators foot. The engagement of the underside of the cap with the end of the hub at 37,

may also serve as a stop to limit the movement of the plunger.

' The primary or main bridging contact is designated 38, and the auxiliary or protective' contact is designated 39. These contacts are preferably in the form of disks,

and a successive engagement of these contacts with the relatively stationary contacts is provided. for by mounting the auxiliary contact on the plunger stem in, advance of the main contact and by stepping the relativel stationary. contacts, providing a seat or the supplementary contact located below and in advance of the seat 41 for \the main contact, the supplementary contact disk being of smaller diameter than the main contact, so as to'pass within the main contact seat 41 without engaging thTa same.

The main bridging contact may be slotted as indicated at 43 to provide a plurality of spring fingers, and may be dished downwardly somewhat as indicated in Fig. 2 to cause said spring fingers to engage the contact surfaces with a yielding wiping action. This main spring contact plate may be. backed up by a reinforcing plate or disk 44.

The auxiliary contact may simply be in" the form of a plain metal disk as indicated,

7 in which case it is preferably backed up by a spring washer 45 or like spring element.

The main and auxiliary contacts are mountedin spaced relation upon the plundisk 45 and auxiliary contact disk 39 are successively engaged, an insulating washer 50 being applied at the lower end of this assemblage and the whole being secured in place as by riveting the reduced end 51 of thev plunger over a metallic holding washer 52.

The two contacts on. the .plunger are spaced apart a greater distance than the stepped contact faces 40 and 41 on the relatively stationary contacts, so that as the plunger is depressed, the lowermost auxiliary contact will first be carried into contact making engagement with the lowermost contact face 40 and thereafter the main bridging contact will be carried into engagement with its seat 41. The yielding mounting for the contacts permits of the contacts adjusting themselves to any inequalities in the contact faces,thus insuring firm, positive electrical engagement. This yielding character of mounting, together with the backing plate 44 protects the con tacts against injury by any undue pressure on the operating stem or plunger, and injury of this character is further positively guarded against by the limiting of the plunger movement through the engagement of the protective cap 34 with the stop shoulders 36 or 37 or'the end of the plunger with the switch base at 53. When pressure on the plunger is released, the restoring spring lifts the plunger, and by reason of the special relation of parts described, separates the main contact from engagement with its contact seat '41, as indicated in Fig. 7. The final break of the circuit is. thus carried by the supplementary contact and the main suited-to the rough service to which such switches are usually subjected, is capable of the combination of a closed switch casing,

a pair of contact plates mounted in spaced relation in said casing and insulated from each other, a plunger mounted in the casing and movable in a plane toward and away from said separated contact plates, a

yielding bridging contact mounted on said plunger and adapted to be carried by ,said plunger into position bridging the separated contact plates, and a backing plate on said plunger at the back of the bridging contact thereon.

2. In a switch of the character described, a closed casing, substantially semi-circular contact plates mounted in spaced relation in the bottom of said casing and insulated from each other, said contact plates having upper substantially semi-circular contactfaces and lower substantially semi-circular contact faces stepped down on a lower plane than the upper contact faces and within the boundary of the upper contact faces, a plunger mounted in the casing, a contact disk on the lower end of the plunger and of less diameter than the upper contact faces to thereby pass down in the movement of the plunger into engagement with the inner lower contact faces, and a contact disk on the plunger above the first contact disk and of larger diameter than said first contact disk to thereby engage the upper cute contact faces.

3. In a switch of the character described,

a switch casing, relatively stationary con-.

tacts in said casing, a. hub extension carried by said casing, a plunger guided in said hub extension, a bridging contact carried by said plunger forQengagement with the relatively stationary contacts, said hub having a reduced upper end and a stop shoulder at the base of said reduced portion, a cap carried by the upper end of the plunger and having a dependent flange sliding over the reduced portion of the hub, the inward movement of said plunger being limited by the engagement of the lower edge of said dependent flange with the shoulder at the base .of the reduced hub portion and a spring acting to thrust the plunger in an outward direction.

4. In a switch of the character described, a switch casing, relatively stationary consaid" plunger being limited by the engagement of the lower edge of said dependent flange with the shoulder at the base of the reduced hub portion, said hub having an annular spring pocket surrounding the plunger and a spring seated in said pocket bearing with its inner end against the inner end of said pocket and hearing at its outer end against the underside of the top of the cap.

5.. In aswitch-of the character described,

a switch casing, switch contacts mounted in spaced relation in said casing and insulated from each other, a plunger; mounted in the casing movable toward and away from saidcontacts, a contact disk mounted on said plunger and of a. size to bridge the switch contacts, said disk being slotted radially to form the same ino a plurality of spring contact fingers, and a relatively rigid supporting plate mounted on the plunger at the back of said slotted contact plate.

6. In a. switch of the character described, a. switch casing, switch contacts mounted in said casing, a plunger mounted in the casing having a movement toward and away from said contacts, a yielding bridging contact on said plunger, a supporting plate at the back of said yielding bridging contact, a supplementary bridging contact mounted on the V plunger in advance of said first bridging contact, and a yielding spacing member between said first and second bridging contacts. 7 In a switch of the character described,

- a switch casing, separated switch contacts mounted therein, a spring pressed plunger mounted in the casing and movable toward and away from said contacts, yielding bridg-. 

